Affinage

YJU2

Splicing factor YJU2 · UniProt Q9BW85

Length
323 aa
Mass
37.1 kDa
Annotated
2026-06-11
20 papers in source corpus 16 papers cited in narrative 16 extracted findings
Cross-family judge vs UniProt: tie faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

Yju2 (human CCDC94) is an essential pre-mRNA splicing factor that promotes the first catalytic step (branching) of the spliceosomal reaction (PMID:19704000). After Prp2-mediated catalytic activation generates high-affinity binding sites on the B* complex (PMID:22535589), Yju2 is recruited to the spliceosome by the NineTeen Complex (NTC), a function requiring the NTC component Ntc90 and acting downstream of activation rather than in activation itself (PMID:19617314, PMID:33705709). Once bound, Yju2 directly contacts U2 snRNA at helix II and the branch-binding region, and structurally it brings the U2/branch-point-sequence duplex into the vicinity of the 5' splice site, positioning the branch-point nucleophile ~4 Å from catalytic metal M2 to enable the first transesterification (PMID:23438600, PMID:30879786); structures of the C complex show it stabilizing branch-helix docking at the Prp8 catalytic cavity alongside Cwc25 and Isy1 (PMID:27459055, PMID:27445308). Yju2 has a modular architecture in which the N-terminal half supports the first step while the C-terminal half mediates tight spliceosome association (PMID:23438600). Progression to the second step requires Prp16- and ATP-dependent remodeling of Yju2 binding, which vacates the active site and is coupled to mutually exclusive exchange of Yju2 for the second-step factor Fyv6 (PMID:21098140, PMID:27980089, PMID:39688371); CCDC94 bridges Prp16 to the active-site RNA during this C-to-C* transition (PMID:29301961). Beyond its splicing role, CCDC94/Prp19 complex localizes to the nucleus and restrains the G1-to-S transition, and protects cells from ionizing-radiation-induced apoptosis by repressing p53 mRNA (PMID:22952453, PMID:16450356).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 2009 High

    Established that Yju2 is an essential first-step splicing factor acting after Prp2 to juxtapose the 5' splice site and branch point, defining where in the catalytic cycle it operates.

    Evidence Depletion/reconstitution with recombinant protein in yeast splicing extracts, with ATP-independent rescue

    PMID:19704000

    Open questions at the time
    • Did not resolve how Yju2 is recruited
    • No structural basis for substrate juxtaposition
  2. 2009 High

    Identified the recruitment mechanism by showing the NTC component Ntc90 is specifically required to load Yju2 onto the activated spliceosome, distinguishing recruitment from activation.

    Evidence Biochemical fractionation, genetic deletion, and reconstitution in yeast extracts

    PMID:19617314

    Open questions at the time
    • Direct Ntc90-Yju2 contact not visualized
    • Order relative to Prp2 action not fully defined
  3. 2010 High

    Showed that Yju2 (with Cwc25) is actively released after step 1 in a Prp16/ATP-dependent manner, establishing release as a prerequisite for the second catalytic step.

    Evidence Biochemical splicing assays with ATP/AMP-PNP and factor addition/depletion in yeast

    PMID:21098140

    Open questions at the time
    • Molecular basis of Prp16-driven destabilization unknown
    • Fate of Yju2 after release not tracked
  4. 2012 High

    Demonstrated that the high-affinity Yju2 binding site is created during Prp2-mediated B* formation, linking catalytic activation to factor recruitment quantitatively.

    Evidence Dual-color fluorescence cross-correlation spectroscopy on purified yeast spliceosomes

    PMID:22535589

    Open questions at the time
    • Did not map the structural elements forming the site
    • Kinetics of in vivo binding not addressed
  5. 2012 Medium

    Extended the function to the human ortholog CCDC94 as a Prp19-complex member with a cellular role in suppressing IR-induced apoptosis via p53 mRNA repression.

    Evidence Zebrafish forward genetic screen, knockdown, RT-PCR for p53 mRNA, rescue

    PMID:22952453

    Open questions at the time
    • Mechanistic link between splicing role and p53 repression unresolved
    • Single lab, organism-specific readout
  6. 2013 High

    Resolved the domain architecture and direct RNA contacts, showing the N-half drives the first step while the C-half confers tight binding, and that Yju2 contacts U2 snRNA helix II and the branch-binding region.

    Evidence Domain dissection with in vivo/in vitro reconstitution, UV cross-linking to U2 snRNA, ATPase bypass assays

    PMID:23438600

    Open questions at the time
    • Atomic geometry of contacts not yet defined
    • Crosslink residues not mapped to specific protein regions
  7. 2016 High

    Cryo-EM of yeast C and C* complexes placed Yju2 structurally, showing it stabilizes branch-helix docking at the Prp8 catalytic cavity for step 1 and dissociates from the active site in C* to admit the 3' exon.

    Evidence Cryo-EM of yeast C complex (3.8 Å, 3.4 Å) and C* complex (4.0 Å)

    PMID:27445308 PMID:27459055 PMID:27980089

    Open questions at the time
    • Pre-branching B* positioning not yet captured
    • Recruitment trajectory not resolved structurally
  8. 2018 High

    Human C-complex structure showed CCDC94 bridges Prp16 to active-site RNA, mechanistically connecting the helicase to the C-to-C* transition in human spliceosomes.

    Evidence Cryo-EM of human C complex at 4.1 Å

    PMID:29301961

    Open questions at the time
    • Dynamics of Prp16-driven remodeling inferred, not directly time-resolved
  9. 2019 High

    B* structures directly demonstrated the catalytic role: Yju2 recruitment brings the U2/BPS duplex toward the 5'SS and positions the branch nucleophile ~4 Å from metal M2.

    Evidence Cryo-EM of four yeast B* complexes (2.9–3.8 Å) with comparative analysis ±Yju2/Cwc25

    PMID:30879786

    Open questions at the time
    • Transition kinetics from recruitment to nucleophile positioning not resolved
  10. 2021 High

    Integrated structure plus biochemistry showed NTC recruits Yju2 before branching and that Prp16 remodels (rather than fully ejects) Yju2, which stays tethered to the NTC in C* to promote exon ligation; co-transcriptional recruitment depends on Rat1.

    Evidence Cryo-EM at 2.8 Å with biochemical C/C* assays; Co-IP/MS and ChIP-Seq for Rat1 interaction in yeast

    PMID:33705709 PMID:33978753

    Open questions at the time
    • Rat1-Yju2 interaction rests on a single Co-IP/MS without reciprocal validation
    • Functional contribution of NTC-tethered Yju2 to step 2 not fully dissected
  11. 2024 High

    Defined the step-1-to-step-2 handoff by showing Yju2 and the second-step factor Fyv6 bind mutually exclusively, so Yju2/Fyv6 exchange drives progression to exon ligation.

    Evidence Cryo-EM of yeast product complex at 2.3 Å with genetic suppressor screen and transcriptomics

    PMID:39688371

    Open questions at the time
    • Trigger that times the exchange not defined
    • Whether NTC-tethered Yju2 directly hands off to Fyv6 unresolved
  12. 2025 Low

    Computational dynamics proposed temporally ordered active-site remodeling by Yju2 with Prp11 and Prp8 to enable step 1.

    Evidence Equilibrium and enhanced-sampling molecular dynamics simulations (>2M atoms) of spliceosome structures

    PMID:41474748

    Open questions at the time
    • Computational only, no experimental validation of Yju2-specific dynamics
    • Predicted residue-level remodeling not tested by mutagenesis

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the human cellular phenotypes of CCDC94 (G1/S restraint and p53-dependent apoptosis protection) mechanistically connect to its conserved spliceosomal branching function remains unresolved.
  • No molecular link established between splicing role and p53 mRNA repression
  • Whether specific intron substrates underlie the cell-cycle phenotype is unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 2
Localization
GO:0005634 nucleus 1
Pathway
R-HSA-8953854 Metabolism of RNA 3 R-HSA-1640170 Cell Cycle 1
Complex memberships
B* complex spliceosomeC complex spliceosomeNineTeen Complex (NTC/Prp19 complex)

Evidence

Reading pass · 16 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2009 Yju2 is required for the first catalytic step of splicing after the action of Prp2, functioning at the final step of the first transesterification reaction. Cwc25 acts after Yju2 in the same step, and both are required for promoting juxtaposition of the 5' splice site and branch point. Depletion/reconstitution assay in yeast splicing extracts; ATP-independent rescue with recombinant protein Molecular and cellular biology High 19704000
2009 Ntc90 (a component of the NineTeen Complex/NTC) is specifically required for recruiting Yju2 to the spliceosome after activation, but not for spliceosome activation itself, revealing a novel NTC role in recruiting first-step splicing factors. Biochemical fractionation, genetic deletion analysis, and reconstitution in yeast splicing extracts RNA (New York, N.Y.) High 19617314
2010 Yju2 and Cwc25 are released from the spliceosome after the first catalytic step in a Prp16- and ATP-dependent manner, and this release is necessary to allow progression to the second catalytic reaction. Biochemical splicing assays with ATP/AMP-PNP, spliceosome purification, and factor addition/depletion in yeast extracts RNA (New York, N.Y.) High 21098140
2012 High-affinity binding sites for Yju2 and Cwc25 are created on the spliceosome during Prp2-mediated catalytic activation (B* complex formation), consistent with their requirement for step 1 catalysis. Dual-color fluorescence cross-correlation spectroscopy (dcFCCS) on purified yeast spliceosomes RNA (New York, N.Y.) High 22535589
2012 Ccdc94 (human ortholog of Yju2) is a functional member of the Prp19 complex, and knockdown of Prp19 complex members increases sensitivity to ionizing radiation-induced apoptosis; Ccdc94/Prp19 complex protects cells from IR-induced apoptosis by repressing p53 mRNA expression. Zebrafish forward genetic screen, genetic knockdown, RT-PCR for p53 mRNA levels, rescue experiments PLoS genetics Medium 22952453
2013 Yju2 has a modular structure: the N-terminal half (Yju2-N) weakly binds the spliceosome and functions in the first step, while the C-terminal half (Yju2-C) stabilizes spliceosome association. Yju2-N alone supports a low level of the second reaction even without Prp16, suggesting that Prp16 acts primarily by destabilizing the C-domain-dependent tight spliceosome binding of Yju2. UV cross-linking shows Yju2 directly contacts U2 snRNA in helix II both pre- and post-catalytically, and contacts the branch-binding region only pre-catalytically. Domain dissection with in vivo and in vitro reconstitution, UV cross-linking to U2 snRNA, ATPase bypass assays in yeast Molecular and cellular biology High 23438600
2006 FLJ10374 (YJU2/CCDC94) localizes exclusively to the nucleus and negatively regulates cell cycle G1-to-S transition; siRNA knockdown increases cell proliferation. Transfection with fluorescence localization, serum-starvation cell cycle assay, siRNA knockdown with proliferation readout Genes, chromosomes & cancer Medium 16450356
2016 Cryo-EM structure of the C complex (post-branching) spliceosome at 3.8 Å shows that Yju2 (along with Isy1 and Cwc25) stabilizes docking of the branch helix, positioning the branch adenosine in the active site and facilitating the first transesterification reaction. Cryo-electron microscopy at 3.8 Å resolution of yeast C complex spliceosome Nature High 27459055
2016 Cryo-EM structure at 3.4 Å of the yeast C complex confirms Yju2 is one of 15 protein components that stabilize specific placement of RNA elements (5'SS, BPS, U5 loop I) at the Prp8 catalytic cavity after the first transesterification reaction. Cryo-electron microscopy at 3.4 Å resolution of yeast C complex spliceosome Science (New York, N.Y.) High 27445308
2016 Cryo-EM structure of the C* complex shows that the step I splicing factors Cwc25 and Yju2 have dissociated from the active site during the C-to-C* transition, vacating space for the incoming 3'-exon sequences required for the second transesterification. Cryo-electron microscopy at 4.0 Å resolution of yeast C* complex spliceosome Science (New York, N.Y.) High 27980089
2018 Cryo-EM structure of the human C complex at 4.1 Å shows that CCDC94 (human Yju2) closely interacts with the DEAH-family ATPase/helicase Prp16 and bridges the gap between Prp16 and the active-site RNA elements, providing mechanistic insight into the C-to-C* transition. Cryo-electron microscopy at 4.1 Å resolution of human C complex spliceosome Science (New York, N.Y.) High 29301961
2019 Cryo-EM structures of four B* complexes at 2.9–3.8 Å reveal that Yju2 recruitment into the active site brings the U2/BPS duplex into the vicinity of the 5' splice site, positioning the BPS nucleophile 4 Å from catalytic metal M2, directly demonstrating Yju2's mechanistic role in promoting the branching reaction. Cryo-electron microscopy of four yeast B* complexes at 2.9–3.8 Å, comparative structural analysis with and without Yju2/Cwc25 Cell High 30879786
2021 Cryo-EM structure at 2.8 Å of the yeast C complex reveals that Yju2 and Isy1 are recruited to the spliceosome by the NTC before branching. After branching, Prp16 remodels Yju2 binding, allowing Yju2 to remain tethered to the NTC in the C* complex to promote exon ligation. Cryo-EM at 2.8 Å combined with biochemical assays for C/C* complex dynamics Molecular cell High 33705709
2021 Rat1 exoribonuclease physically interacts with the Yju2 splicing factor (co-immunoprecipitation and mass spectrometry), and is required for proper co-transcriptional recruitment of splicing factors including Yju2 to introns. Co-immunoprecipitation, mass spectrometry, ChIP-Seq in yeast Nucleic acids research Medium 33978753
2024 Cryo-EM structure of a yeast product complex spliceosome at 2.3 Å shows that binding of the second-step factor Fyv6 to the spliceosome is mutually exclusive with that of the first-step factor Yju2, and that Yju2/Fyv6 exchange facilitates progression from the first to the second step of splicing. Cryo-EM at 2.3 Å, genetic suppressor screen, transcriptomics eLife High 39688371
2025 Molecular dynamics simulations integrating cryo-EM data reveal that Yju2 acts in a temporally ordered fashion with Prp11 and Prp8 at the spliceosome core, with positively charged residues in these proteins dynamically remodeling the active site to enable the first step of splicing. Equilibrium and enhanced sampling molecular dynamics simulations (>2M atoms) of multiple spliceosome structures Proceedings of the National Academy of Sciences of the United States of America Low 41474748

Source papers

Stage 0 corpus · 20 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2016 Cryo-EM structure of the spliceosome immediately after branching. Nature 198 27459055
2016 Structure of a yeast catalytic step I spliceosome at 3.4 Å resolution. Science (New York, N.Y.) 158 27445308
2016 Structure of a yeast step II catalytically activated spliceosome. Science (New York, N.Y.) 121 27980089
2018 Structure of a human catalytic step I spliceosome. Science (New York, N.Y.) 119 29301961
2010 DEAH-box ATPase Prp16 has dual roles in remodeling of the spliceosome in catalytic steps. RNA (New York, N.Y.) 84 21098140
2012 Prp2-mediated protein rearrangements at the catalytic core of the spliceosome as revealed by dcFCCS. RNA (New York, N.Y.) 75 22535589
2009 Cwc25 is a novel splicing factor required after Prp2 and Yju2 to facilitate the first catalytic reaction. Molecular and cellular biology 71 19704000
2019 Structures of the Catalytically Activated Yeast Spliceosome Reveal the Mechanism of Branching. Cell 69 30879786
2021 Structural basis for conformational equilibrium of the catalytic spliceosome. Molecular cell 46 33705709
2022 Whole genome sequencing identifies candidate genes for familial essential tremor and reveals biological pathways implicated in essential tremor aetiology. EBioMedicine 22 36183486
2012 Ccdc94 protects cells from ionizing radiation by inhibiting the expression of p53. PLoS genetics 22 22952453
2013 A weak spliceosome-binding domain of Yju2 functions in the first step and bypasses Prp16 in the second step of splicing. Molecular and cellular biology 18 23438600
2009 Ntc90 is required for recruiting first step factor Yju2 but not for spliceosome activation. RNA (New York, N.Y.) 16 19617314
2014 Remodeling of U2-U6 snRNA helix I during pre-mRNA splicing by Prp16 and the NineTeen Complex protein Cwc2. Nucleic acids research 13 24848011
2006 Three-way translocation involves MLL, MLLT3, and a novel cell cycle control gene, FLJ10374, in the pathogenesis of acute myeloid leukemia with t(9;11;19)(p22;q23;p13.3). Genes, chromosomes & cancer 8 16450356
2024 Control of 3' splice site selection by the yeast splicing factor Fyv6. eLife 6 39688371
2021 A termination-independent role of Rat1 in cotranscriptional splicing. Nucleic acids research 6 33978753
2025 Controlled dynamic remodeling of the spliceosome active site enables the first step of splicing. Proceedings of the National Academy of Sciences of the United States of America 2 41474748
2025 Identification of Therapeutic Targets for Premature Ovarian Failure Through Mendelian Randomization and Colocalization Analysis Using Human Plasma Proteomics. Journal of molecular neuroscience : MN 0 40883588
2024 Control of 3' splice site selection by the yeast splicing factor Fyv6. bioRxiv : the preprint server for biology 0 38746449

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